"PathScale announced today that the EKOPath 4 Compiler Suite is now available as an open source project and free download for Linux, FreeBSD and Solaris. This release includes documentation and the complete development stack, including compiler, debugger, assembler, runtimes and standard libraries. EKOPath is the product of years of ongoing development, representing one of the industries highest performance Intel 64 and AMD C, C++ and Fortran compilers." More here.

AFAIK these are the source code repositories for path64 compiler and debugger. However, unless I'm mistaken not all proprietary path64 features has yet been added to this repo but they will be (it's after all the whole point of this announcement).